The replacement of natural vessels with prosthetic materials introduces two new interfaces to the recipient biological system: the blood-material interface on the lumen side and the tissue-material interface on the exterior surface. During the past decade a substantial effort has been made to find more acceptable materials and designs for vascular prostheses, especially for the smaller vessels. Most of the effort has been focused on developing more 'blood-compatible' surfaces while the tissue-material interfacial response has usually been assumed to be controlled by the so-called "foreign-body response". This proposal is based on the assumption that control of the tissue reaction will become more crucial to the ultimate success of the vascular prosthesis as more blood compatible materials are developed. The mechanisms responsible for initiation and resolution of the fibrous capsule around the prosthetic vessel and the relationship between these mechanisms and the material properties of the implant material are now only slightly better understood than when the initial attempt was made to replace a natural vessel with a synthetic material. The objective of this study is to establish the relationship between specific, controlled materials properties such as charge, hydrophilicity and surface morphology and the biological response of certain cells known to be involved in the formation of the fibrous capsule. The rate and the extent of cell adhesion will be determined by radiolabelled kinetic attachment assays. The cell morphology during attachment will be observed using scanning microscopy. The rates and orientations of cell motility will be determined at or near the surface of the material using time-lapse microcinematography. The extent of enzymatic activity will be measured using hollow fiber flow chambers. Cell types will include fibroblasts, macrophages and neutrophils. This three year, in vitro study has been designed to answer specific questions about the mechanisms of cellular interactions with materials currently in use or under investigation as potential vessel replacements.